Bread toaster



May 22, 1962 Original Filed Dec. 31, 1954 J. J. LAWSER BREAD TOASTER 4Sheets-Sheet 1 May 22, 1962 J. J. LAWSER 3,035,509

BREAD TOASTER Original Filed Dec. 51, 1954 4 Sheets-Sheet 2 J. J. LAWSERBREAD TOASTER May 22, 1962 4 Sheets-Sheet 4 Original Filed Dec. '31,1954 Fig q United States Patent Ofiice 3,035,509 Patented May 22, 19623,935,509 BREAD TOASTER John J. Lawser, Dearborn, Mich assignor to TheProctor-Siiex Corporation, a corporation of Pennsylvania flriginaiapplication Dec. 31, 1954, Ser. No. 473,094, new

Patent No. 2,951,432, dated Sept. 6, 1960. Divided and this applicationSept. 25, 1959, Ser. No. 842,291

6 Claims. ((31. 99-329) This invention relates to automatic breadtoasters and, more particularly, to electric bread toasters of the typeemploying a bread-sensitive thermostat to control the length of thetoasting cycle.

This invention relates to a bread toaster having at least one bread ovenand electric heating elements on opposite sides of the oven. A breadcarriage including a bread supporting rack is arranged for movement tocarry a slice of bread from a bread receiving to a bread toastingposition in the oven and back to bread receiving position aftertoasting. A bread temperature-responsive thermostat is located adjacentthe oven disposed in close proximity to the bread slice when in toastingposition. The invention concerns the provisions of a shield carried bythe carriage and extending from the rack generally in the direction ofmovement of the bread carriage as it is moved from bread receiving tobread toasting position and so positioned that it is in close proximityto the thermostat to drain heat therefrom when the carriage is in breadreceiving position. This action enables immediate proper response by thethermostat as successive pieces of bread are moved into toastingposition. It also shields the thermostat from direct radiation from oneof the heating elements. Without such an aid to thermostat recoveryimproper responses by the thermostat, such as failure to permit latchingin bread toasting position, or other faulty operation of thermostatdependent apparatus, may result.

The primary object of the invention is to provide novel means forcooling the thermostat to prevent spurious release of the bread carriageat the beginning of a toasting cycle.

Other objects and features of the invention will be apparent from thedescription to follow.

In the accompanying drawings:

FIG. 1 is an end view of a toaster structure embodying the invention,with the outer casing and base shown in dot-and-dash outline;

FIG. 2 is a cross-sectional view taken centrally through the toasterstructure;

FIG. 3 is a sectional view taken along line 33 of FIG. 1;

FIG. 4 is a sectional view taken along line 4--4 of FIG. 3, showing thelower portion of the toaster;

FIG. 5 is a bottom view of the toaster with a portion of the crumb traybroken away for the purpose of illustration;

FIG. 6 is a perspective view of the bread-sensitive thermostat;

FIG. 7 is a plan view of the carriage-releasing electromagnet;

FIG. 8 is a side elevational view of the electromagnet, with the casingbroken away and with some parts sectionalized for the purpose ofillustration;

FIG. 9 is an exploded perspective view of some of the parts'of theelectromagnet;

FIG. 10 is an isometric view of the heating elements and the electricalbus arrangement employed; and

FIG. 11 is a diagrammatic illustration of the electrical circuit.

Certain features of the toaster disclosed herein are disclosed andclaimed in a copending application of H. F. Hild et al., Serial No.480,118, filed January 6, 1955, now U .5. Patent No. 2,951,436, issuedSeptember 6, 1960, and in my copending application, Serial. No. 479,004,filed December 31, 1954, now United States Letters Patent No. 2,951,432.For the present purpose, a general description of the toaster structurewill suifice.

Referring first to FiGS. 1 to 5, there is illustrated a twowell toasterhaving a base 20 formed of insulating material, a support chassis 21supported by the base, a frame 22 supported by the chassis, and anoutershell 23 supported by the base and serving to enclose the internalstructure. The frame provides two bread wells 24 and 25 within whichbread slices 26 and 27 may be inserted. Grille wires 28, 29 and 30, 31,supported by the frame 22, serve to define the two bread wells. A breadcarriage 32, having bread-supporting racks 33 and 34 within the twobread wells, serves to support the bread slices. The carriage isconnected through link 35 to a lever 36 pivoted at 37 and 33 as shown inFIG. 3 to the frame 22. The carriage is urged upwardly by a spring 39,and it is moved downwardly to lower the bread slices to toastingposition by means of a manually-operable member 40 connected to lever36. As shown in FIG. 1, the carriage is held in the toasting position bya latch mechanism comprising a latch element 41 pivotally mounted on thecarriage to rot-ate about pivot '41a and including a hooked lower endwhich is hooked beneath ledge 42a of cooperating latch element 42mounted on a stationary pivot 4-3 as the carriage reaches its lowermostposition. Release of the latch mechanism at the end of the toastingoperation permits the bread carriage to be moved upwardly by spring 39,thus raising the bread slices. A dashpot 44, connected to lever 36,serves to limit the speed of upward movement of the carriage.

The control of the toasting operation is performed by thebread-sensitive thermostat '45 positioned adjacent one of the breadwells, and by the electromagnet 46 which controls the latch mechanism.During the toasting operation, latch element 42 is held against upwardmovement about its pivot 43 by the armature 47 of the electromagnet,which is then deenergized. At the end of the toasting operation, theelectromagnet is energized by closure of switch elements 48 and 49controlled by the thermostat. Energization of the electromagnet causesmovement of its armature 47 out of engagement with latch element 42, asindicated in broken lines toward the bottom of FIGURE 1, permitting thelatter to swing upwardly under the force of spring 39, and the latch elements 41 is thus freed and the bread carriage is permitted to rise.

It should be noted that latch element 42 is of substantial length and itis engageable by latch element 41 near the pivot 43 and by the armature47 relatively remote from said pivot. By virtue of this arrangement,only a small resisting force is required to be exerted on the armatureto maintain engagement of the latch elements, and only a small force isrequired to be exerted by the electromagnet to eifect disengagement ofsaid elements. Thus, the work load of the electromagnet is reduced andthe latter may operate on low voltage and low cur rent.

For selection of desired toast color, the toaster P eferably employs anadjusting mechanism designatedgenerally by reference numeral 50, whichis disclosed and claimed in my above-mentioned.application.

The Toaster Circuit Referring now to FIGS. 10 and 11, thecircuitcomprises a service cord 51 for connection to a supply line, aswitch 52 operated by lever 36, which is closed when the carriage is inits lowered position and opened upon raising of the carriage, outerheating elements 53 and 54 and the center heating element 55. The outerheating elements 53 and 54 are serially connected across the supplyline, while the center heating element 55 is connected directly acrossthe supply line. The heating elements 53 and 54 are electricallyinterconnected by a bus 56 (see also FIGS. 2 and 3). This bus isgenerally T- shaped and is made of aluminum or similar material. Its

7 arms are connected, as by screws 57 and 58 to heating elements 53 and54, respectively. The center leg of bus 56 iselectrically andmechanically connected to the base of the thermostat 45. Screws 59secure the thermostat to the bus, and also secure the entire assembly tothe chassis 21 of the toaster, as may be seen in FIG. 4. The bus iselectrically insulated from the chassis by insulating spacers 60 and 61.The thermostat is included in a shunt circuit about heating element 54,which circuit also includes the switch 48, 49 and the releaseelectromagnet 46. Bus bar 62 is used to connect the service connectionto one end of heating element 53 and one end of heating element 55,while bus 63 connects the opposite end of heating element 55 and one endof heating element 54 to the service connection.

With the service connection 51 connected to a source of electricity,lowering of the bread carriage will eifect closing of switch 52. Thiswill cause current to flow simultaneously through parallel circuitbranches, one extending through the series-connected heating elements 53and 54 and the other extending through the center heating element 55.Upon heating of the bread-sensitive thermostat 45, switch 48, 49 isclosed, causing current to flow through the electromagnet 46. Thevoltage applied to the shunt circuit through the electromagnet is thatacross heating element 54. This is substantially onehalf of theoperating voltage, since heating elements 53 and 54 are series connecteddirectly across the line and are substantially equal in resistance. Byusing a high resistance winding in electromagnet 46, an extremely lowcurrent is drawn thereby upon closure of switch 48, 49. This avoids anyappreciable arcing at the switch contacts. Upon energization of theelectromagnet, the bread carriage is raised, effecting opening of theswitch 52 to deenergize the heating elements and also the electromagnet.

The disposition of the T-shaped bus member 56, which is in effect acenter tap between the two outer heating elements 53 and 54, with itsarms extending across the bottoms of the bread wells, permits it torespond to the general heat of the toaster. Securing of the thermostatto this bus helps the support for the thermostat to sense effectivelythe toaster ambient temperatures.

Further details of the mounting of the thermostat 45 and the adjustmentof contact 49 may be had by referring to my above-mentioned copendingapplication.

The Electromagnet In FIGS. 1 and 3, it will be seen that theelectromagnet 46 is mounted on the chassis 21 adjacent one of the endwalls of the frame 22 and between the latter and the casing 23. Thislocation has proven by test to be one of the coolest within the toasterand was, therefore, chosen for the location of the electromagnet.Electromagnet 46 (see FIGS. 7 to 9) consists essentially of a winding64, a core 65 riveted to a bracket 66, and the armature 47. The bracket66 is secured to the chassis 21, as by a bolt 67, and is indexed theretoby projections 68 formed in the bracket and adapted to seat in recessesin the chassis. The armature 47 is of inverted U-shape and is slotted at69 to receive a tongue-like extension 70 of bracket 66. Captured betweenthe armature 47 and the shoulders 71 of the tongue-like extension 70 isa curved spring element 72 suitably slotted at 73. The mounting ofarmature 47 on extension 71 provides a pivotal support for the armature.To hold the armature in place, and to prevent crumbs from entering theelectromagnet mechanism, a shield or cover 74 is provided which extendsalong the sides and one end of the electromagnet assembly, beinggenerally U-shaped. The cover is held on the bracket 66 by tabs 76 whichproject through apertures 77 in the bracket and are twisted.

The free end of armature 47 engages the free end of latch element 42when the electromagnet is deenergized. In FIG. 8, the solid lineillustration shows the latch-engaging position of the armature. When theelectromagnet is energized, the armature is pulled toward the core 65,thereby rotating the armature about the shoulders 71 of the tongue-likeextension 70. This causes release of latch element 42 which, aspreviously mentioned, is then free to swing upward under the force ofspring 39.

Spring 72 biases the armature toward the latch-engaging position. Thisspring is made of non-magnetic spring material, and it also serves toprevent sticking of the armature to the core 65 due to residualmagnetism therein. The magnetic circuit can be traced as follows: Onenergization of electromagnet coil 64, lines of flux are set up throughthe core 65, through the upper portion of bracket 66, across air gapformed at the pivotal mounting of the armature, through the armature andthence across the air gap to the pole face 78 of the core 65. It shouldbe noted that the pivotal mounting of the armature has low friction andalso provides effective sealing against entrance of crumbs. The coil 64of the electromagnet is made from wire covered with high temperatureinsulation, such as nylon.

The Thermostat The bread-sensitive thermostat 45 represents animprovement to that disclosed and claimed in the W. H. Vogelsberg PatentNo. 2,667,115, which issued January 26, 1954. In FIGS. 2 and 4 thethermostat is shown to comprise a support 79 which is secured to thechassis 21 but is electrically insulated therefrom, as hereinbeforedescribed. As may be seen in FIG. 6, the upper portion of support 79 isinclined at 80 and terminates in a shield 81. Secured at incline 80 area bimetallic member 82, which is the thermomotive member of thethermostat, and another shield member 83. The latter two members arerigidly fixed to the support 79 as by spot welding. Shields 81 and 83are disposed on opposite sides of the bimetallic member 82 and arespaced therefrom. The spacings between the bimetallic member and theshields were carefully ascertained from optimum performance of thethermostat. For example, with a bimetal member of .025" thickness,shields 81 and 83 are approximately .040" thick Ms" wide, and are spacedat the top respectively and A3" from the vertical axis of thethermostat.

The bimetal member 82 is generally of inverted U form, and thesupporting leg 84 thereof serves as the compensating or secondary leg.The rigid securing of the compensating leg 84 and the support 79, andthe close thermal association of said support and the bus 56 assuresthat the compensating leg shall receive temperature intelligence that inefiect is a true measure of the ambient temperature of the toaster. Thepurposes of the shields 81 and 83 are to provide a thermal lag to thecompensating leg of the thermostat and also to minimize the amount ofdirect radiation that the compensating leg receives from the heatingelement 55 which is directly back of the thermostat. Previous attemptsat shielding the compensating portion have resulted in devices that giveinconsistent coupling effect between the shield and the compensator.Loose shielding parts added to the compensator also, through friction,added hysteresis to the move ment of the compensating leg. The presentshield construction obviates the objections of prior devices. With thecompensating leg 84 of the thermostat secured at its bottom to thesupport 79 and with its high expansion side disposed toward the right inFIG. 4, its upper end will move toward the left on heating, and thuswill move closer to shield 83 and farther from shield 81. On cooling,the reverse action will occur. By this arrangement a substantiallyconstant coupling between the shields and the compensating leg isobtained.

The bimetallic member 82 also has a reinforcing flange 85 and a primaryleg 86. The primary leg responds to the bread temperature and, similarto the compensating leg, flexes in a plane parallel to the planes of thebread slices and the heating elements to etfect movement of contact 48toward contact 49. As may be seen in FIG. 4, primary leg 86 of thethermostat has secured thereto, as by welding, an L-shaped rod 87 whichis effectively an extension of the prim-ary leg and which carriescontact 48. The latter is preferably a small piece of circular platinumwire of approximately .015" diameter, which is secured, as by spotwelding, to extension 87 and has a sharp sheared tip for optimum contactoperation. The tip flexes toward the stationary contact 49 which is madepreferably of fine silver. The use of the circuit and electromagnetrelease as hereinbefore described requires that the contact 48 merelyengage contact 49 to cause release of the bread carriage. The arcingload on the contacts, because of the circuit used, is kept quite small.However, to obviate the effect of film buildup and to break down surfaceoxides and other films that may accumulate on the contacts as a resultof the toasting operation, the sharp point is provided on contact 48 asdescribed above. A shield 88 additionally protects stationary contact 49from crumbs falling directly upon said contact.

By reducing the work load on the thermostat, it is possible to reducethe cross-section of the legs of the bimetal and thereby its speed ofresponse. Reduction in mass of the thermostat improves the ability ofthe thermostat to track the surface temperature of the bread slice 27that is placed in front of it, as may be seen in FIG. 2, and furtherincreases the speed of cooling of the thermostat at the end of thetoasting cycle. To further promote rapid cooling of the thermostat, arectangular shield or plate 89 is secured to the bottom of breadcarriage below bread rack 34 (see FIGS. 2 and 4). During the toastingoperation, shield 89 is positioned near the base of the toaster. At theend of the toasting cycle when the carriage is in its top position, theshield 89 is located adjacent the primary leg 86 of the thermostat, inthe dotted line position in FIG. 2. The primary leg 86 then loses itsheat by radiation to the shield 89. The shield also prevents radiantenergy from the heating element 53, which would be still arm, fromimpinging on the primary leg 86 of the thermostat. When the carriage isin its lower position, the shield 89 is adjacent a plate 90 which ismounted on the frame of the toaster and is stationary. During thetoasting operation, plate 90 shields plate 89 against radiant energyfrom heating element 55. Plate 90 also cooperates with a louvre 91 inthe crumb tray 92 to create a draft of cool air from beneath the toasterto plate 89 and maintain the latter at a relatively low temperature. Theplate 90 is spaced relatively close to shield 89 when the latter is inits lower position and the two thereby provide a relatively highresistance path for air flow therebetween. Further, plate 90 extendsbelow the shield 89 and is practically adjacent the crumb tray 92. Thearrangement of the plate 90, the shield 89 and the louvre 91 preventsthe air draft from rising past the thermostat during toasting operationto spuriously affect its performance. On the other hand, it creates aflow of air past the right hand side of shield 89 (FIG. 2) and up theright hand side of the bread slice 27. An additional louvre 93 isprovided in the crumb tray and an additional stationary plate 94 isprovided, so that balanced parallel drafts of air are produced upward inboth bread wells. Additional louvres 95 and 96 (FIG. 4) are provided inthe crumb tray to assist in cooling the end plates of the toaster andalso in creating drafts to help carry away moisture and other volatileproducts of the toasting operation. By reducing the mass of thethermostat and by quick cooling action of plate 89, the thermostat iscaused to be extremely reliable and quickly responsive. Thus, spuriousre-releasing of the carriage on insertion of a fresh bread slice isobviated.

While a preferred embodiment of the invention has been illustrated anddescribed, the invention is not limited thereto, but contemplates suchmodifications and other embodiments as may occur to those skilled in theart.

I claim:

1. In a bread toaster having at least one bread oven and heatingelements on opposite sides of the oven, a bread carriage including abread-supporting rack arranged for movement to carry a bread slice froma bread receiving position to a bread toasting position in the oven andto carry the bread slice back to bread receiving position aftertoasting, -a bread temperature-responsive ther mostat adjacent said'oven disposed in close proximity to the bread slice when the latter isin toasting position, and a shield carried by said carriage, extendingfrom said rack generally in the direction of movement of the breadcarriage as it is moved from bread receiving to the bread toastingposition arranged to be in close proximity to said thermostat to drainheat therefrom when the carriage is in bread receiving position.

2. In a bread toaster having at least one bread well and heatingelements on opposite sides of the well, a bread carriage including abread-supporting rack arranged for vertical movement to carry a breadslice downward into the well and to carry the bread slice upward aftertoasting, a bread temperature-responsive thermostat adjacent said welldisposed in close proximity to the bread slice when the latter is intoasting position, and a shield carried by said carriage and extendingdownward from said rack arranged to be in close proximity to saidthermostat to drain heat therefrom when the carriage is raised.

3. A toaster according to claim 2 further comprising a stationary memberso positioned that a large area of the stationary member will beopposite and close spaced to the shield when the bread carriage is intoasting position.

4. A toaster according to claim 3 further comprising a bottom wall forthe toaster having louver means positioned therein so that the openingof the louver means is adjacent the side of the shield farthest from thestationary member when the carriage is in lowered position to effect anupward draft primarily on one side of said shield.

5. In a two-well bread toaster having a center heating element and outerheating elements, a bread carriage arranged for vertical movement tocarry bread slices downward into the Wells and to carry the bread slicesupward after toasting, lowers at the bottom of the toaster andstationary members projecting upward into said wells arranged to effectbalanced parallel upward air drafts to the bread wells, a breadtemperature-responsive thermostat adjacent one of said wells arranged inconfronting relation to a bread slice on the carriage when the carriageis lowered, and a shield carried by said carriage and extendingdownwardly therefrom, said shield being disposed in said well andarranged to be adjacent a large area on one of said stationary memberswhen the carriage is lowered and to be adjacent said thermostat to drainheat therefrom when the bread carriage is raised.

6. In a bread toaster having at least one bread well and heatingelements on opposite sides of the well, a bread carriage arranged forvertical movement to carry a bread slice downward into the Well and tocarry the bread slice upward after toasting, a breadtemperatureresponsive thermostat adjacent said well including a bimetalmember disposed in close proximity to the bread slice when the latter isin toasting position, and a shield carried by said carriage andextending downward therefrom disposed in said Well arranged to be inclose proximity to said bimetal member when the carriage is raised, saidshield being of such proportions as to prevent substantially the heatradiation of one of said heating elements from impinging on said bimetalmember while draining heat therefrom.

References Cited in the file of this patent UNITED STATES PATENTSStevenson Nov. 4, 1952 Hill Jan. 6, 1953 Rouse Feb. 23, 1954 Palmer Dec.23, 1958

